Vinylacetylene-terminated polymide derivatives

ABSTRACT

Novel, unsaturated vinylacetylene-terminated polyimides and processes for their preparation are disclosed herein. These new polyimides are derivatives of anhydride-terminated aromatic polyimides from which they can be prepared by amidation to provide new unsaturated amide groups having a terminal group containing the structure --CH═CH--C.tbd.C-- or --C.tbd.C--CH═CH--, hereinafter sometimes referred to as &#34;conjugated enynes&#34;. These new compositions are more tractable than the original anhydride-terminated polyimides and can be converted at appropriate lower temperatures to crosslinked, insoluble, infusible polymers without by-product formation, thereby extending greatly the applications for which the aromatic polyimides can be employed. Moreover, these new polyimides can undergo the Diels-Alder type of addition with a large number of dienophiles. Certain monomeric materials are also described.

This application is a continuation-in-part of copending application Ser.No. 199,616 filed Oct. 22, 1980, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to new polymeric compositions derived fromaromatic polyimides containing terminally unsaturated groups. Morespecifically, it relates to such polymers derived from polyimidecompositions in which the terminal groups are moieties that containterminal enyne functions capable of polymerizing and forming crosslinkedpolymers. Still more specifically, it relates to such crosslinkedpolymers obtained therefrom without the formation of by-products.

2. State of the Prior Art

Polyimides, as prepared from aromatic dianhydrides and aromaticdiamines, are known to have the desired property of high heat resistanceand high solvent resistance. Such polyimides, upon condensation to aninfusible condition, generate by-products such as water and other vaporsor gases which introduce voids into the fabricated products that detractfrom the expected good physical properties. In addition, because ofthese same desirable properties, they are untractable and, therefore,very difficult and expensive to work into desired shapes and forms.

Recent patents, such as U.S. Pat. Nos. 3,845,018, 3,864,309, 3,879,395and 3,998,786 are directed to improving the tractability of the aromaticpolyimides by attaching various terminal groups to polyimide oligomerswhereby the chains are extended by coupling of the terminal groups. Inthese patents the coupling groups are attached as terminal imidemoieties containing vinyl, ethynyl, nitrile, etc. groups. Thus theterminal anhydride group is converted to an imide group containing avinyl, nitrile, ethynyl, etc. group. However, in none of these patentsnor in any other related prior art references, has there been found anyreference or disclosure that the terminal anhydride group on each endcould be converted to a terminal imide group containing avinylacetylenic or enyne moiety possessing a --CH═CH--C.tbd.C-- orinterchangeably a --C.tbd.C--CH═C-- structure.

Previous publications (A. L. Landis, et al, Polymer Preprints 15, 533(1974), 15, 537 (1974) describing acetylene-terminated polymers assumedthat the cure reaction involved a simple trimerization of three terminalacetylenic end-groups into an aromatic crosslink, thus: ##STR1##

When model compounds, such as phenyl acetylene and others are subjectedto "cure" conditions (Technical Report AFML-TR-76-71 June 1976, pp.8-11, 21-22), they do not give rise to the formation of singificantquantities of trimerized products as has been assumed. In addition tomajor amounts (90%) of polymeric material, there is isolated smallquantities of complex mixture of products. It has been shown thatterminated acetylene groups can simultaneously react by a number ofalternate routes, such as by:

1. Glaser coupling (G. Glaser, Ann. 137, 154 (1870), (which in thepresence of air is referred to as oxidative coupling): ##STR2##

2. Strauss coupling (F. Straus Ann. 342, 190 (1905)) ##STR3##

3. Straus or Glaser product reaction (Chemistry of Acetylenes, H. G.Viehe, ed., Marcel Dekker, N. Y. 1969): ##STR4##

In order to determine the possibility that Straus or Glaser linkages areinitially formed which then undergo further reaction and rearrangements,the model compounds ##STR5## were prepared and subjected to cureconditions (Technical Report AFML-TR-76-71 June 1976). Model compound A,the Glaser coupling, produces 100% polymers. Model compound B, theStraus coupling, also produces polymers along with small amounts ofphenyl naphthalene. These and DSC analysis indicate that thecrosslinking reaction of the terminal acetylene group is much morecomplex than originally assumed and apparently proceeds by a number ofsimultaneously mechanistic routes. Thus, if the polyimide containsterminal C.tbd.CH groups, and in the cure reaction there is producedGlaser or Straus couplings in the cured products, sensitivity to oxygenat high temperatures is to be expected. Thermogravimetric analysis of apolymer derived from:

    HC.tbd.C--C.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 --OCC.sub.6 H.sub.3 (CO).sub.2 N(C.sub.6 H.sub.4 O).sub.2 C.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 --.sub.n OCC.sub.6 H.sub.3 (CO).sub.2 NC.sub.6 H.sub.4 C.tbd.CH

shows (Technical Report AFML-TR-75-30, July 1975, p. 61) that 75% of thesample weight is lost in the interval 560°+90° C. and that unusualbehavior occurs above the region of the weight loss, indicating weightgain and that "the cause should be investigated".

Accordingly, it would appear to be a worthwhile technical objective toachieve the synthesis of polyimides which are devoid of terminalacetylenic structures, that is mono- acetylene --CH.tbd.CXH, but whichstill can undergo practical desirable acetylene-type chemistry toachieve the crosslinking of the polyimide. We have now discovered thatthis objective can be achieved by end-capping the polyimides with groupscontaining the vinylacetylene or enyne structure: --CH═CH--C.tbd.C-- orinterchangeably --C.tbd.C--CH═CH--.

SUMMARY OF THE INVENTION

In accordance with the present invention, it has been found thatinsoluble, infusible polymerization products are readily obtained bypolymerizing polyimides having terminal groups which contain conjugatedvinylacetylene or enyne structures --CH═CH--C.tbd.C-- or--C.tbd.C--CH═CH--.

The unsaturated crosslinkable polyimides of this invention have theformula (I): ##STR6## wherein:

Ar' is a tetravalent aromatic organic radical, the four carbonyl groupsbeing attached directly to separate carbon atoms and each pair ofcarbonyl groups being attached to the adjacent carbon atoms in Ar'radical except in the case of Ar' being a naphthalene radical, one orboth pairs of the carbonyl groups may be attached to peri carbon atoms;

Ar is a divalent aromatic organic radical;

n is zero or an integer of 1 to 20, preferably 1 to 10;

R is hydrogen or an organic moiety containing 1 to 21 carbon atoms; and

Z is the structure --CH═CH--C.tbd.C-- or interchangeably--C.tbd.C--CH═CH--.

In the Z structure, the vinyl portions, --CH═CH--, can be considered asthe head portion and the acetylene portion, --C.tbd.C-- as the tailportion and thus Z can be attached to --AR-- and --R in a head-to-headorientation, thus --ArCH═CH--C.tbd.C--R or in a tail-to-headorientation, thus --Ar--C.tbd.C--CH═CH--R. In addition, the structure--CH═CH--C.tbd.C-- isomerizes easily to --C.tbd.C--CH═CH--,

    --CH═CH--C.tbd.C--⃡--C.tbd.C--CH═CH--.

In this invention, the term vinylacetylene or enyne, when shown as--CH═CH--C.tbd.C-- is meant to include the structure --C.tbd.C--CH═CH--as its equivalent.

When n is zero in Formula I, the polyimide is the monomer of thestructure (II): ##STR7## When n is greater than zero, n may beidentified as n".

The polyimides (I) are concurrently prepared by amidation and imidationof the anhydride terminated compounds of the formula (III): ##STR8##wherein n, Ar and Ar' have the same meaning as in (I), thus when n=0,III reduces to: ##STR9## Amidation of (III) is accomplished by reaction(Eq. 1) with a monoamine H₂ N--Ar--ZR, wherein Ar, Z and R have the samemeaning as in I, the amidation occurs in the terminal anhydride groupfirst with the formation of a terminal hemi-amic acid (V), thus:##STR10## which, on dehydration, has ring closure to give the imidestructure (VI): ##STR11## Also, the imides of this invention can beprepared by amidating the amine-terminated polyimide oligomers of theformula VII: ##STR12## wherein n, Ar and Ar' have the same meaning as inFormula (1) with an unsymmetrical aromatic dianhydride monoimide of theformula (VIII): ##STR13## wherein Ar, Ar', Z and R have the same meaningas in Formula (I), thus ##STR14## which is dehydrated (Eq. 4) to theimide (X) ##STR15## The dehydration of the hemi-amic acids shown inEquations 2 and 4 can be achieved thermally or by chemical dehydrationas, for example, by use of acid anhydrides, for example, aceticanhydride, propionic anhydride, or by azeotropic distillation asdescribed in more detail hereinafter.

In the preparation of the enyne end-capped polyimides of this invention,tetra-esters or acid chlorides with a hydrohalide acceptor may be usedinstead of the dianhydrides. For preparing alcohol soluble oligomers,the dianhydride may be converted to an alcohol soluble hemi-ester byreaction with a lower aliphatic alcohol: ##STR16## which is reacted at aratio of n+1 moles with n moles of H₂ NArNH₂ and two moles of H₂ NArZ--Rand concentrated to a syrup which is useful as a laminating resin.

The amine-terminated oligomers (VII) used hereinabove as intermediatesin the preparation of the polyimide (I) of this invention, asillustrated by Equation 3, are prepared by reacting a molar excess,i.e., n+1 moles of an aromatic diamine, H₂ NArNH₂, with n moles of anaromatic dianhydride ##STR17## wherein Ar and Ar' have the same meaningas defined heretofore, and the aromatic diamine and the aromaticdianhydrides are the same pair of co-reactants used to prepare theanhydride-terminated oligomers represented by Formula III. The polyimideamine-terminated oligomers (VII) used as intermediates may beconveniently prepared by the same process used to synthesize theanhydride-terminated polyimides (III) used as intermediates foramidation except for the molar ratio of amine and anhydride used. Thesesyntheses are exemplified in U.S. Pat. Nos. 3,897,395 and 3,058,505 andhereinafter with specific reference, for example, to the synthesis ofthe anhydride terminated polyimides.

The polyimide anhydrides (III) used in the above reactions in thesynthesis of (I) of this invention are prepared by reacting a molarexcess, i.e., n+1 moles of an aromatic dianhydride with n moles of anaromatic diamine. The aromatic dianhydride has the formula: ##STR18##wherein Ar' is a tetravalent aromatic organic radical, preferablycontaining at least one ring of six carbon atoms, said ringcharacterized by benzenoid unsaturation, the four carbonyl groups beingattached directly to separate carbon atoms and each pair of carbonylgroups being attached to adjacent carbon atoms in the Ar' radical exceptthat when Ar' represents the naphthalene radical, one or both pairs ofcarbonyl groups may be attached to the peri carbon atoms.

The aromatic diamines useful in this preparation are represented by theformula H₂ N--AR--NH₂ wherein Ar is a divalent aromatic organic radical.

In preparing the anhydride-terminated polyimides, any of the aromatictetracarboxylic acid dianhydrides known in the prior art can be used.Among the useful dianhydrides are 3,3',4,4'-benzophenonetetracarboxylicacid dianhydride, 1,4,5,6-tetracarboxylic dianhydride,3,3',4,4'-diphenyl tetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 2,2',3,3,'-diphenyl tetracarboxylicacid dianhydride, 2,2-bis(3,4-dicarboxyphenyl) propane dianhydride,3,4,9,10-perylene tetracarboxylic acid dianhydride,bis(3,4-dicarboxyphenyl) ether dianhydride,naphthalene-1,2,4,5-tetracarboxylic acid dianhydride,naphthalene-1,4,5,8-tetracarboxylic acid dianhydride,decahydronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride,4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylicacid dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic aciddianhydride, phenanthrene-1,8,9,10-tetracarboxylic acid dianhydride,cyclopentane-1,2,3,4-tetracarboxyphenyl) propane dianhydride,1,1-bis(2,3-dicarboxyphenyl) ethane dianhydride,1,1-bis(3,4-dicarboxyphenyl) ethane dianhydride,bis(2,3-dicarboxyphenyl) methane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, andbenzene-1,2,3,4-tetracarboxylic acid dianhydride. The first threementioned dianhydrides are preferred.

Aromatic diamines useful in preparing the starting polyimides have theformula:

    NH.sub.2 --AR--NH.sub.2

wherein Ar is a divalent aromatic organic radical. Preferred aromaticdiamines are those wherein Ar is a divalent benzenoid radical selectedfrom the group consisting of: ##STR19## and multiples thereof connectedto each other by R^(III), e.g., ##STR20## wherein R^(III) is --CH═CH--,##STR21## or an alkylene chain of 1-3 carbon atoms, wherein R^(V) andR^(VI) are each selected from the group consisting of alkyl and arylcontaining one to six carbon atoms, e.g., methyl, ethyl, hexyl, n-butyl,i-butyl and phenyl. Preferred Ar' groups are: ##STR22##

Examples of the aromatic diamines which are suitable for use in thepresent invention are 4,4'-diaminodiphenyl propane,4,4'-diamino-diphenyl methane, benzidine, 3,3'-dichlorobenzidine,4,4'-diamino-diphenyl sulfide, 3,3'-diamino-diphenyl sulfone,4,4'-diamino-diphenyl ethyl phosphine oxide, 4,4'-diamino-diphenylphenyl phosphine oxide, 4,4'-diamino-diphenyl N-methyl amine,4,4'-diamino-diphenyl N-phenyl amine and mixtures thereof,3,3'-dimethyl-4,4'-diaminodiphenylmethane,3,3'-diethyl-4,4'-diaminodiphenylmethane,3,3'-dibromo-4,4'-diaminodiphenylmethane,3,3'-dicarboxy-4,4'-diaminophenylmethane,3,3'-dihydroxy-4,4'-diaminophenylmethane,3,3'-disulpho-4,4'-diaminodiphenylmethane,3,3'-dimethyl-4,4'-diaminodiphenylether,3,3'-diethyl-4,4'-diaminodiphenylether,3,3'-dimethoxy-4,4'-diaminodiphenylether,3,3'-diethoxy-4,4'-diaminodiphenylether,3,3'-dichloro-4,4'-diaminodiphenylether,3,3'-dibromo-4,4'-diaminodiphenylether,3,3'-dicarboxy-4,4'-diaminodiphenylether,3,3'-dihydroxy-4,4'-diaminodiphenylether,3,3'-disulfo-4,4'-diaminodiphenylether,3,3'-dimethyl-4,4'-diaminodiphenylsulfide,3,3'-diethyl-4,4'-diaminodiphenylsulfide,3,3'-diethyl-4,4'-diaminodiphenylsulfide, 3,3'-dimethoxy-4,4'-diaminodiphenylsulfide, 3,3-diethoxy-4,4'-diaminodiphenylsulfide,3,3'-dichloro-4,4'-diaminodiphenylsulfide,3,3'-dibromo-4,4'-diaminodiphenylsulfide,3,3'-dicarboxyyl-4,4'-diaminodiphenylsulfide,3,3'-dihydroxy-4,4'-diaminodiphenylsulfide,3,3'-disulfo-4,4'-diaminodiphenylsulfide,3,3'-dimethyl-4,4'-diaminodiphenylsulfone,3,3'-diethoxy-4,4'-diaminodiphenylsulfone,3,3'-dichloro-4,4'-diaminodiphenylsulfone,3,3'-dicarboxy-4,4'-diaminodiphenylsulfone,3,3'-dihydroxy-4,4'-diaminodiphenylsulfone,3,3'-disulfo-4,4'-diaminodiphenylsulfone,3,3'-diethyl-4,4'-diaminodiphenylpropane,3,3'-dimethoxy-4,4'-diaminodiphenylpropane,3,3'-dibromo-4,4'-diaminodiphenylpropane,3,3'-dichloro-4,4'-diaminodiphenylpropane,3,3'-dicarboxy-4,4'-diaminodiphenylpropane,3,3'-dihydroxy-4,4'-diaminodiphenylpropane,3,3'-disulfo-4,4'-diaminodiphenylpropane,3,3'-dimethyl-4,4'-diaminobenzophenone,3,3'-dimethoxy-4,4'-diaminobenzophenone,3,3'-dichloro-4,4'-diaminobenzophenone,3,3'-dibromo-4,4'-diaminobenzophenone,3,3'-dicarboxy-4,4'-diaminobenzophenone,3,3'-dihydroxy-4,4'-diaminobenzophenone,3,3'-disulphodiaminobenzophenone, 3,3'-diaminodiphenylmethane,3,3'-diaminodiphenylether, 3,3'-diaminodiphenylsulfide,3,3'-diaminodiphenylsulfone, 3,3'-diaminodiphenylpropane,3,3'-diaminobenzophenone, 2,4-diaminotoluene, 2,6-diaminotoluene,1-isopropyl-2,4-phenylenediamine, 2,4-diaminoanisole,2,4-diaminomonochlorobenzene, 2,4-diaminofluorobenzene,2,4-diaminobenzoic acid, 2,4-diaminophenol and2,4-diaminobenzenesulfonic acid and phenylene diamines. Preferreddiamines are 4,4'-oxydianiline, 4,4'-sulfonyldianiline, 4,4'-methylenedianiline, 4,4'-diaminobenzophenone, 4,4'-diaminostilbene and thephenylene diamines, 2,4-diaminotoluene and all the meta and para isomersof H₂ NC₆ H₄ OC₆ H₄ OC₆ H₄ NH₂.

The R goups may include any organic moiety that will not interfere withthe functions of the polyimides as described herein. Preferably thesegroups are hydrocarbon or a multiplicity of hydrocarbon groups joined byether, sulfite, ester and sulfonyl groups, such as --O--, --S--,--COO--, --OOC--, --S(O)₂ --, etc.

Typical R groups suitable in the above formulas include: --CH₃, --C₂ H₅,--C₃ H₇, --C₄ H₉, --C₆ H₁₃, --C₁₀ H₂₁, --C₁₈ H₃₇, --C₆ H₁₁, --C₅ H₉,--C₅ H₈ CH₃, --C₆ H₁₀ C₂ H₅, --CH₂ C₆ H₁₁, --CH₂ CH₂ C₆ H₁₁, --C₆ H₅,--C₆ H₄ CH₃, --C₆ H₄ C₃ H₇, --C₆ H₃ (CH₃)₂, --C₆ H₉ OCH₃, --C₆ H₄ OC₂H₅, --C₆ H₄ OOCCH₃, --C₆ H₄ SO₂ C₆ H₅, --C₆ H₄ SO₂ C₆ H₄ CH₃, --C₆ H₄SO₂ C₆ H₅, --C₆ H.sub. 4 SO₂ C₁₀ H₇, --C₆ H₄ OC₆ H₅, --C₆ H₄ OC₆ H₅,--C₆ H₄ OCH₃, --C₆ H₄ OC₂ H₅, --C₆ H₃ (CH₃)OC₃ H₇, --C₆ H₄ OC₆ H₄ CH₃,--C₁₀ H₈, --C₁₀ H₇ CH₃, --C₁₀ H₇ C₂ H₅, --C₁₀ H₆ (CH₃)₂, --C₁₀ H₆ OCH₃,--C₁₀ OOCCH₃, --(C₆ H₄)₃ C₃ H₇, --(C₆ H₄)₃ OC₄ H₉, --(C₆ H₄)₃ OC₆ H₅,--C₆ H₄ (OCH₂ CH₂)₂ H, --C₆ H₄ (OCH₂ CH₂)₃ H, --(C₆ H₄ O)₃ C₃ H₇, --CH₂CH₂ (OCH₂ CH₂)₂ H, --CH₂ CH₂ (OCH₂ CH₂)₃ OOCCH₃, --CH₂ CH₂ OC₆ H₅, --CH₂CH₂ OOCCH₃, --CH₂ CH(CH₃)OOCC₆ H₅, --C₆ H₄ COOC₂ H₅, --CH₂ COOC₆ H₅,etc.

The polyimide starting materials used in the process of this inventionmay be prepared conveniently as shown in U.S. Pat. Nos. 3,897,395 and4,058,505 by reacting the dianhydride with the diamine in a phenolsolvent of the formula: ##STR23## wherein each R^(I) is hydrogen or amethyl radical, in the presence of certain organic azeotroping agents,particularly cyclic hydrocarbons of 6 to 8 carbon atoms and mostpreferably benzene or toluene, until most of the water of reaction iseliminated. The reaction temperature is less than 140° C. and alsoshould be below the boiling point of the phenol used but higher than theboiling point of the azeotroping agent. The vapor phase temperature liesbetween that of the water azeotrope and no higher than 95° C. As thewater of reaction and azeotroping agent are removed from the reactionmixture, quantities of the azeotroping agent are removed from thereaction mixture, quantities of the azeotroping agent are returned tothe reaction mixture so as to maintain the temperature and reactionmixture volume substantially constant. It is preferred that the processis continuous with continuous removal of water and continuous return ofazeotroping agent. This is conveniently done by the use of aconventional Dean-Stark trap and condenser wherein after the azeotropecondenses, the water preferably sinks to the bottom of the trap forsubsequent removal and the azeotroping agent overflows the trap andreturns to the reaction mixture. Initially, the trap is filled withazeotroping agent. For brevity, this apparatus will be referred toherein as cresol-benzene azeotropic apparatus.

By using an excess of the anhydride, the terminal groups of thepolyimide will be anhydride groups. The more excess there is of theanhydride, the shorter will be the molecular length of the polyimide.Advantageously, the amount of excess anhydride is calculated inaccordance with the desired length or molecular weight of the desiredstarting polyimide.

Similarly, by using an excess of the diamine, the terminal groups of thepolyimides will be amine groups. The more excess there is of thediamine, the shorter will be the molecular length of the polyimide.Advantageously, the amount of excess diamine is calculated in accordancewith the desired length or molecular weight of the desired startingpolyimide.

It is apparent from an observation of compounds of the Formulas I to Xand of Equations 1 to 4, that the polyimides of this invention are thereaction product of:

n moles of H₂ NArNH₂,

N+1 moles of ##STR24## and

2 moles of H₂ NArZ--R

which can be reacted in stages as shown hereinabove, or can be reactedas a mixture in a single step or can react in a series of steps in asingle reactor, particularly by using the azeotropic technique describedabove. For example, 2 moles of H₂ NArZR can be reacted first with n+1moles of ##STR25## and thereafter n moles of H₂ NArNH₂ added and thereaction completed in which the linkages formed can be either hemi-amicor imide; or n moles of H₂ NArNH₂ are first reacted with n+1 moles of##STR26## and thereafter 2 moles of H₂ NArZ--R are added and thereaction completed.

A few illustrative examples of the monoamines, H₂ NArZ--R whichintroduce the terminal NArZ--R moieties in the polyimides (I) of thisinvention are:

H₂ NC₆ H₄ CH═CH--C.tbd.CH

H₂ NC₆ H₄ CH═CH--C.tbd.CC₆ H5

o-H₂ NC₆ H₄ OC₆ H₄ CH═CH--C.tbd.CC₆ H₅

m-H₂ NC₆ H₄ OC₆ H₄ CH═CH--C.tbd.CC₆ H₅

p-H₂ NC₆ H₄ OC₆ H₄ CH═CH--C.tbd.CC₆ H₅

H₂ NC₆ H₄ SO₂ C₆ H₄ CH═CH--C.tbd.CC₆ H₅

H₂ NC₆ H₄ CH═CH--C.tbd.C--C₆ H₄ OC₆ H₅

H₂ NC₆ H₄ CH═CH--C.tbd.C--C₆ H₄ SO₂ C₆ H₅

H₂ NC₆ H₄ OC₆ H₄ CH═CH--C.tbd.C--C₆ H₄ SO₂ C₆ H₅

H₂ NC₆ H₄ SO₂ C₆ H₄ CH═CH--C.tbd.CC₆ H₄ SO₂ C₆ H₅

H₂ NC₆ H₄ SO₂ C₆ H₄ CH═CH--C.tbd.CC₆ H₄ OC₆ H₅

H₂ NC₆ H₄ OC₆ H₄ CH═CH--C.tbd.C--C₆ H₄ OC₆ H₅

H₂ NC₆ H₄ CH═CH--C.tbd.CC₁₈ H₃₇

H₂ NC₆ H₄ CH═CH--C.tbd.C--C₆ H₄ C₆ H₄ C₆ H₅

H₂ NC₆ H₄ CH═CH--C.tbd.C(C₆ H₄)₃ C₃ H₇

H₂ NC₆ H₄ CH═CH--C.tbd.C(C₆ H₄ O)₃ C₃ H₇

H₂ NC₆ H₄ CH═CH--C.tbd.C--CH₃

H₂ NC₆ H₄ OC₆ H₄ OC₆ H₄ CH═CH--C.tbd.CC₆ H₅

Compounds of the formula H₂ NZR wherein Z is --CH═CH--C.tbd.C--, arereadily prepared by partial reduction by hydrogen of the precursordiacetylene compounds H₂ NArC.tbd.C--C.tbd.CR by the procedure used byStraus for the conversion of C₆ H₅ C.tbd.C--C.tbd.CC₆ H₅ to C₆ H₅CH═CH--C.tbd.C--C₆ H₅ (Acetylene Homologues et Derives, by PierrePiganiol, Dunod Publisher 1945, Paris, pp. 138-139). In thediacetylenes, which are not symmetrical such as in H₂ NC₆ H₄C.tbd.C--C.tbd.CC₆ H₅, reduction in many cases yield two vinylacetylenes, thus:

    H.sub.2 NC.sub.6 H.sub.4 CH═CH--C.tbd.CC.sub.6 H.sub.5 and H.sub.2 NC.sub.6 H.sub.4 C.tbd.C--CH═CHC.sub.6 H.sub.5

which for the purposes and objectives of this invention are equivalent.

The vinyl acetylene aryl amines, H₂ NArZH, are also convenientlyprepared by using the procedure of U.S. Pat. No. 4,162,265 which usesNH₂ ArC.tbd.CH as the starting material, then protects the amino group,e.g., by conversion to CH₃ CONHArC.tbd.CH, followed by coupling withcopper catalysis in an inert atmosphere to yield CH₃CONHArCH═CH--C.tbd.C--ArNHOCCH₃ Partial hydrolysis yields CH₃CONHArCH═CH--C.tbd.CArNH₂ and H₂ NArCH═CHC.tbd.CArNHOCCH₃. Thendiazotization and treatment with alcohol yields CH₃CONHArCH═CH--C.tbd.ArH and CH₃ CONHArC.tbd.C--CH═CHArH. Furtherhydrolysis yields the isomeric H₂ NArCH═CH--C.tbd.CArH and H₂NArC.tbd.CCH═CHArH. The amino aryl diacetylene compounds which can bereduced by partial hydrogenation to the corresponding vinyl acetylenecompounds as shown hereinabove, are prepared by well known chemicalreactions which involve coupling of monoacetylenic compounds havingterminal --C.tbd.CH or --C.tbd.CX functions wherein X is a halogen suchas iodine, bromide or chlorine.

Ref. 1. Acetylenic Compounds in Organic Synthesis, by R. A. Raphael,Butterworths Scientific Publications, 1955, London; and

Ref. 2. Acetylene Homologues et Derives, by Pierre Piganiol, Dunod 1945,Paris.

One method involves converting the 1-haloacetylene to a Grignardderivative, R^(V) C.tbd.C--MgX, and reacting it with the1-halogeno-acetylene R^(VI) C.tbd.CX thus,

    R.sup.V C.tbd.CMgX+R.sup.VI C.tbd.CX→MgX.sub.2 +R.sup.V C.tbd.C--C.tbd.CR.sup.VI

Ref. 3. Liebigs, Ann 572, 116 (1951)

Ref. 4. J. Chem. Soc. (1954) 1704

where R^(V) and R^(VI) represent moieties having carbon atoms attachedto the --C.tbd.C-- function and, in some cases, hydrogen. Instead of theGrignard reagents, an alkali acetylide, such as sodium, potassium orlithium acetylide can be used, thus:

    R.sup.VI C.tbd.CX+R.sup.V C.tbd.CNa→NaX+R.sup.IV C.tbd.C--C.tbd.CR.sup.IV

(See R. A. Raphael in Ref. 1, p. 16, and Bull. Soc. Chem. 53, 1533-1537(1933), and J. Chem. Soc. (1946) 1009.

Also, the diacetylenes undergo similar reaction and can be converted tothe 1-halogenoacetylide or alkali acetylides, thus, ##STR27## (See J.Chem. Soc., p. 44 (1951), p. 1933 (1952) and Chem. Ber. 84, 545 (1951. )

The nitroaryl acetylenes, O₂ NArC.tbd.CH can be subjected to coupling togive:

    O.sub.2 NArC.tbd.C--C.tbd.CArNO.sub.2

and

    O.sub.2 NArC.tbd.C--C.tbd.CR

which on reduction of the nitro groups, yield the amines:

    H.sub.2 NArC.tbd.C--C.tbd.CArNH.sub.2

and

    H.sub.2 NArC.tbd.C--C.tbd.CR.

These diamines and monoamines are new chemical compounds.

When H₂ NArC.tbd.CH is used in a coupling reaction, the H₂ N group mustfirst be blocked so that it will not interfere with the couplingreaction, as for example, to an amide or imide function such as theacetamide, toluenesulfonamide or the phthalimide, thus, ##STR28## Thesecompounds having one or two cyclic imide terminal groups are veryuseful, including the corresponding naphthalene ortho and pericompounds. Hydrolysis with alcoholic or aqueous sodium hydroxideliberates the free amide to give, e.g.,

H₂ NArC.tbd.C--C.tbd.CArNH₂ from the first three equations, and

H₂ NArC.tbd.C--C.tbd.CC₆ H₅ from the fourth equation.

This procedure of coupling amide derivatives of acetylenic compounds isillustrated in U.S. Pat. No. 4,162,625 where the coupling is performedin an inert atmosphere to produce vinyl acetylene derivatives,--C.tbd.C--CH═CH--. The same procedure when performed in an oxygenatmosphere produces diacetylene --C.tbd.C--C.tbd.C--.

Conjugated diacetylene can also be prepared by the so-called oxidativecoupling of monoacetylenes having a terminal --C.tbd.CH function, thus##STR29##

One procedure involves mixing the ethynyl compound with an aqueoussolution of cuprous chloride in an atmosphere of oxygen. Acetylenes ofwidely varying structural types have been prepared by this method(Reference 1, p. 127). The use of two different acetylenic components inthe coupling reaction produces some cross-coupling and the expectedthree di-acetylenes are obtained, such as the two symmetricaldiacetylenes shown above and the unsymmetrical product R^(V)C.tbd.C--C.tbd.CR^(VI). These products are readily separated on thebasis of size and the type of substituents R^(V) and R^(VI) (Reference1, p. 128). Sometimes the mono-acetylene is converted to the copperderivative and the copper compounds subjected to coupling in thepresence of air (oxygen). For the amines of the formula H₂ N--Z--R usedin the practice of this invention, the amine aryl acetylenes H₂NArC.tbd.CH are satisfactory intermediates for conversion to thediacetylene and the vinylacetylene compounds. These NH₂ ArC.tbd.CHcompounds are readily obtained by reacting O₂ NArCOCH₃ with PCl₅ oroxalyl chloride in dimethylformamide followed by treatment with alkalito give O₂ NArC.tbd.CH. The NO₂ group is easily reduced by sodiumdithionate. Alternatively, the NO₂ group can be left unreduced untilcoupling is completed and then the NO₂ group reduced to --NH₂.

The diamino-diacetylenes are useful intermediates for preparing themono-amino compounds by first protecting one amino group by amideformations and thereafter converting the remaining amino group to adiazonium salt followed by reacting with ethyl alcohol to eliminate N₂yielding the hydrocarbon functions, thus when J represents CH₃ CO-- orCH₃ C₆ H₄ SO₂ -- and Q is ##STR30## Cross-coupling (oxidative coupling)of an amide of the aminoaryl acetylene, J--NHArC.tbd.CH or Q═NArC.tbd.CHwith a different acetylene compound free of amide or amine group,RC.tbd.CH, produces the unsymmetrical cross-coupled product,J--NHArC.tbd.C--C.tbd.CR or Q═NArC.tbd.C--C.tbd.CR, which on hydrolysisgive H₂ NArC.tbd.C--C.tbd.CR as well as the two symmetrical products,one of which, as shown above, on hydrolysis gives the diamino derivativeH₂ NArC.tbd.C--C.tbd.CArNH₂ useful per se as a diamine in polyamide andpolyimide syntheses as well as the symmetrical RC.tbd.C--C.tbd.CR whichis free of amino-groups. This latter compound is useful as a chemicalintermediate and can also function as a "dieneophile" and as a di-yne.It can function as Diels-Alder donor compound and function as acoreactive plasticizer for all types of polymers containing terminal orpendant CH₂ ═CH--, CH₂ ═C<, --CH═CH--, --C.tbd.CR groups.

The nature of the reactivity of the terminal --CH═CH--C.tbd.C--structures in the polyimides of this invention differs substantiallyfrom polyimide compounds having a terminal monoacetylenic structure--C.tbd.C--.

The 1,3 enyne character of --CH═CH--C.tbd.C-- qualifies it as a donortype of molecule in the Diels-Alder type reaction so that it is capableof undergoing a 1,4 addition reaction with olefinic unsaturatedcompounds known as dienophiles, such as those containing CH₂ ═C,--CH═CH--, and --C.tbd.C-- structures. The dienophile is activated byelectro withdrawn substituents such as --COOR, --CN, --C₆ H₅, --CONR₂,--SO₂, etc. (Reference: Organic Chemistry, Cram and Hammond, McGraw-HillPublisher, New York, 1959; also Organic Chemistry, Fieser and Fieser,Reinhold Publishing Company, New York, 1961, p. 206-11). Typicalexamples of the Diels-Alder reaction are the reaction of butadiene andmaleic anhydride to give 1,2,3,6-tetrahydrophthalic anhydride, thus:##STR31## and the related reactions with an acetylene dicarboxylate togive a 1,2,3,6-dihydrophthalate diester, thus, ##STR32## or the reactionof diacetylene with maleic anhydride to give phthalic anhydrides, thus,##STR33## Furthermore, the enyne compounds of this invention canfunction as the "dienophile" in a Diels-Alder reaction either withanother Diels-Alder donor, e.g., a compound containing butadiene,--CH═CH--CH═C-- structure, or with itself as a compound containing anenyne --CH═CH--C.tbd.C-- structure. Thus a vinylacetylene structure,--CH═CH--C.tbd.C-- can function both as a "diene" or as a "dienophile"or as both, in reactions which offer another route to benzenoidderivatives. (See Ref. 1 above, p. 160-VSW and for Comprehensive Reviewssee H. L. Holmes, Organic Reactions 4, 60 (1948) and K. Alder, NewMethods of Preparative Organic Chemistry, New York, 1948, p. 381 VSW).In contrast, a compound having a single --C.tbd.C-- structure, canfunction only as the dienophile and not as a donor in the Diels-Aldertype reaction.

Accordingly, it has been discovered that the polyimides of thisinvention are capable of undergoing this Diels-Alder type of reactionwith a large variety of dienophiles whether they are monomeric,oligomeric or polymeric, or whether they are monofunctional orpolyfunctional, e.g., difunctional, trifunctional, etc. Thepolyfunctional dienophiles chain extend and crosslink the polyimides ofthis invention. Such addition products can be viewed in a broad sense ascopolymers. However, they differ from the accepted type of copolymerwhich is obtained by chain formation with the opening of a double ortriple bond, whereas in the Diels-Alder reaction there occurs theformation of six-membered rings.

A large number of dienophiles are available for the 1,4-cycloaddition tothe polyimides of this invention. One particularly useful class is theclass of maleimide end-capped polyimides having the formula: ##STR34##wherein Ar and Ar' are the same as those given in formula (I) hereinabove and n' is equal to n of formula (I). The syntheses of a number ofmaleimides illustrative of XI are given in U.S. Pat. No. 3,929,713, Dec.30, 1975.

Another useful class is that having the formula: ##STR35## wherein Ar'and Ar have the same meaning as in Formula I and R' is an organic moietycontaining 1 to 12 carbon atoms, and n' has the same meaning as n. Thepreferred examples of R' are --CH₂ -- and --C₆ H₄ --. The syntheses of anumber of polyimides, illustrative of XII, are given in U.S. Pat. No.3,897,395, July 29, 1975.

A third useful class of polyimides that can function as dienophiles isgiven by the formula: ##STR36## wherein n' has the same meaning as n,and Ar', Ar and n have the same meaning as in Formula I, R' is the sameas in Formula XII, i.e. a divalent organic moiety containing 1 to 12carbon atoms. R° is H or R wherein R has the same meaning as in FormulaI. The preferred examples of R' are --CH₂ -- and --C₆ H₄ -- and thepreferred examples of R° are H, --C₆ H₅ and --C₆ H₄ --O--C₆ H₅. Thesynthesis of dienophile polyimides of this type is described in U.S.Pat. Nos. 3,987,395 and 3,845,018.

A still further useful class of polyimides that function as dienophilesis that given by the formula: ##STR37## wherein n' has the same meaningas n, and Ar, Ar' and n are the same as given in Formula I, and R"'represents R°C.tbd.CAr<, R°CH═CHAr<, e.g., C₆ H₅ .tbd.CC₆ H₃ <, H₂C═CHC₆ H₃ <, HC.tbd.CC₆ H₄ OC₆ H₃ <, C₆ H₅ OC₆ H₄ C.tbd.CC₆ H₃ <, CH₃C.tbd.CC₆ H₄ C₆ H₃ <, H₂ C.tbd.CHC₆ H₃ <, HC.tbd.CC₆ H₄ OC₆ H₃ <, C₆ H₅OC₆ H₄ C.tbd.CC₆ H₃ <, CH₃ C.tbd.CC₆ H₄ C₆ H₃ <, C₃ H₇ C.tbd.CC₆ H₃ <,C₆ H₅ SO₂ C₆ H₄ C.tbd.CC₆ H₃ <, CH₃ C₆ H₄ CH═CHC₆ H₃ <, C₆ H₄ OC₆ H₄CH═CHC₆ H₃ <, H(CH₂ CH₂ O)₂ -- CH₂ CH₂ CH═CHC₆ H₃ <, etc. wherein R° isthe same as defined for R.

Some polyimides of this class are disclosed in U.S. Pat. No. 4,075,171.

Other CH₂ ═C<, --HC═CH--, --C.tbd.C--, and CH.tbd.C-- terminatedpolyimides useful as dienophiles in the practice of this invention aregiven in U.S. Pat. Nos. 4,166,168; 4,168,360; 4,168,366; 4,168,367 and3,998,786.

It is also to be noted that since many simple monomers contain suchgroups as CH₂ ═C<, HC.tbd.C--, --C.tbd.C-- or >C═C<, they can functioneither as comonomers or as dienophiles for addition reaction with thenew polyimides of this invention. For purposes of this invention suchmonomers may be classified as having RCH═C(R°)-- or RC.tbd.C-- groupswherein R and R° are as defined above (representing either hydrogen oran organic moiety having 1-20 carbon atoms).

Some typical monomers are the maleyl compounds such as maleic anhydride##STR38## and its esters, ##STR39## wherein R^(IV) is an organic moietycontaining 1 to 21 carbon atoms; the maleimides such as ##STR40## theacetylenic carboxylic esters, R^(IV) C.tbd.C--COOR^(IV) ; R^(IV)OOCC.tbd.C--COOR^(IV) ; the dimaleimides ##STR41## wherein Ar is asdefined in Formula (I); and the end-capped polyimides selected from theclass of oligomers and polymers derived from the reaction of n moles ofAr(NH₂), n+1 mole of Ar (CO)₂ O and 2 moles of a monoaryl amine havingmono --CH═CH-- or mono --C.tbd.C-- unsaturation as well as the monomersof this reaction when n equals zero.

Some other illustrative examples are styrene, the divinyl benzenes, thediethynyl benzenes, methyl methacrylate, glycoldimethacrylate,allylmethacrylate, acrylamide, ethylenediamine dimethacrylamide,acrylonitrile, maleic anhydride, diethyl maleate, diallyl fumarate,dipropargyl phthalate, dibutyl itacomate, a poly(ethylene-maleate), apoly(ethylenefumarate), 4,4'-diethynyl diphenyloxide, diphenyl maleate,N-phenyl maleimide, N-(vinyl phenyl) maleimide, N-(ethynylphenyl)maleimide, dipropargyl maleate, diallyl maleate, the acetylenic esterssuch as HC.tbd.CHCOOCH₂ CH═CH₂, C₆ H₅ C.tbd.C--COOCH₂ CH═CH₂, C₆ H₅C.tbd.COOCH₂ C.tbd.CH, HC.tbd.C--C₆ H₄ OOCC.tbd.CCOOC₆ H₄ .tbd.CH, H₂C═CHC₆ H₄ OOCC.tbd.C--COOC₆ H₄ CH═CH₂, etc. In the vinylidene (CH₂ ═C<)monomers, one valence bond is preferably attached to hydrogen to give avinyl monomer. However this bond may also be attached to various othergroups such as hydrocarbyl groups of 1-20 carbon atoms, including alkylaryl, cycloalkyl, alkenyl, etc., halogen, cyano (CN), OR, OOCR, CONR₂,COOR, etc. Other typical compounds are methyl alpha-chloroacrylate,methyl alpha-cyanoacrylate, alpha-methylstyrene, alpha-ethylstyrene,alpha-phenylstyrene, methacrylonitrile, dimethyl methylene-malonate,diethyl itaconate, vinyl benzoate, isopropanyl acetate,dimethylacrylamide, etc.

The Diels-Alder addition product usually is formed by the equimolarreaction of one donor function --CH═CH--C.tbd.C-- with one dienophilefunction, e.g., one CH₂ ═CH--, or one --C.tbd.C--, or one ##STR42##function. Thus two donor functions react with two dienophile functions.However, since the donor polyimides of this invention, and thedienophile acceptors are capable of homopolymerization, mixtures inwhich either the donor or acceptor functions are in a minor or in a verylarge excess, completely polymerize by Diels-Alder addition togetherwith the normal double and triple bond polymerization. Thesepolymerizations occur by simply heating the mixture of reactants.

The products of this invention can be converted to the insoluble,infusible state by heat alone, such as by heating at temperatures in therange of 180° C. to 380° C., or even at lower temperatures, such as 100°C. or 200° C. or, if desired, by the addition of catalysts that generatefree radicals such as benzoyl peroxide, the perbenzoates, cumyl mono anddiperoxides, and a host of others that are well known in the vinylmonomer art, which include redox systems which promote polymerization ofCH.tbd.C-- containing monomers at or even below room temperature, or byionizing radiation or ultraviolet radiation, etc.

In many cases it may also be desirable to post-cure the products withinthe same range of temperatures or even higher temperatures, e.g. up to425° C.

These products can be compounded with fillers of all sorts in thepreparation of molding compounds, such as with graphite and quartzfibers or fillers to maintain high temperature resistance, etc.

The products of this invention are particularly useful as coatings andbonding agents for metals such as iron, copper, aluminum, steel, etc.,either alone or as mixtures with other compounds containing two to fourterminal ##STR43## structures.

The new polyimides of this invention can be used as varnishes andcoatings in appropriate solvents which depend on the nature of theconstituent diamine and dianhydrides used in the synthesis of thepolyimide esters.

In most cases the solvent is a aprotic organic compound having adielectric constant between 35 and 45, preferably one which iswater-soluble. Representative aprotic compounds areN,N-dimethylformamide, N,N-diethylformamide,N,N-dimethylmethoxyacetamide, N-methyl caprolactam, caprolactam,N,N-dimethylacetamide, N,N-diethylacetamide, dimethyl sulfoxide,N-methyl-α-pyrrolidone, tetramethylurea, hexamethylphosphonamide,tetramethylene sulfone, N,N,N',N'-tetramethylethylmalonamide,N,N,N',N'-tetramethylglutaramide, N,N,N',N'-tetramethylsuccinamide,thiobis(N,N-dimethylacetamide), bis(N,N-dimethylcarbamylmethyl) ether,N,N,N',N'-tetramethylfuraramide, methylsuccinonitrile,N,N-dimethylcyanoacetamide, N,N-dimethyl-β-cyano-propionamide,N-formyl-piperdine and butyrolactone, etc.

Of the solvents, dimethylacetamide is most preferred. Other preferredsolvents are dimethylformamide, N-methyl pyrrolidinone, dimethylsulfoxide, butyrolactone and caprolactate.

In many cases, non-aprotic solvents may also be used. For example,xylene, phenol, anisole, benzonitrile, acetophenone, methylphenylether,methylene chloride, chloroform, carbon tetrachloride or mixtures ofthese with each other, with the aprotic solvents or with relatively poorsolvents such as benzene, toluene, cyclohexane, cyclohexene, dioxane,butyl cellosolve and the like.

SPECIFIC EMBODIMENTS OF THE INVENTION

The invention is illustrated by the following examples which areintended merely for purposes of illustration and are not to be regardedas limiting the scope of the invention or the manner in which it may bepracticed. Unless specifically indicated otherwise, parts andpercentages are given by weight.

EXAMPLE I Preparation of Anhydride-Terminated Oligomeric Polyimide #1

Into a 100 ml. three-neck, round bottom flask equipped with a magneticstirrer, thermometer, condenser, gas inlet tube, dropping funnel, etc.there is placed, under nitrogen atmosphere, a solution ofbenzophenonetetracarboxylic acid anhydride (BTCA) (6.444 g., 0.02 mole)in 25 ml. of dimethylacetamide (DMAC). Then a solution of4,4'-oxydianiline (ODA) (2.00 g., 0.01 mole) in 15 ml. of DMAC is addedover a period of 15 minutes. The reaction, which is exothermic, ismaintained at 40° C. during the addition, following which it is heatedat 85°-90° C. for 15 minutes. To this clear ambercolored solution,acetic anhydride (3.60 g., 0.03 mole) is added and the mixture is heatedto 125° C. Within 15 minutes a yellow precipitate is formed. Afterheating the reaction mixture for one hour, the solvents are removed in arotary flash evaporator. The residual light-yellow solid is washed withanhydrous ether and dried in a vacuum oven at 140° C. to afford aquantitative yield. It softens slightly on a Fisher-Johns melting pointapparatus at 120° C. and does not melt when heated to 300° C. Theproduct is soluble in m-cresol and N-methyl-2-pyrrolidone and onlyslightly soluble in boiling benzonitrile, acetophenone or DMAC. Theelemental analysis is found to be for C: 68.3% and for H: 2.4%, which isin good agreement with the calculated values for C₄₆ H₂₀ N₂ O₁₃ havingthe formula:

    O(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 NC.sub.6 H.sub.4 OC.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 O

EXAMPLE II Preparation of Hemi-Amide of Polyimide of Example I

Into the reaction equipment used in Example I there is placed 50 ml. ofN-methyl-2-pyrrolidone, 4.04 gm. of polyimide #1, 2.17 gm. of m-H₂ NC₆H₄ CH═CH--C.tbd.CC₆ H₅ and the mixture is heated at 100° C. for 10minutes or until a clear solution is obtained. Water:methanol is addedto the precipitate and washes the product which is isolated byfiltration and dried in a vacuum oven at 110°-120° C. to give an almostquantitative yield of 6.0 g. The elemental analysis of 75.26% carbon and3.36% hydrogen are in good agreement with the calculated values for C₇₈H₄₂ N₄ O₁₃ having the formula: ##STR44##

EXAMPLE III Cyclization of Hemi-Amide of Example II

Using the m-cresol-benzene azeotropic technique, there is allowed toreact at reflux 6.0 g. of the hemi-amid of Example II in 40 ml. ofm-cresol and 10 ml. of benzene until no more water is collected in theDean-Stark trap. The benzene is removed by distillation andmethanol:water is added to the reaction flask and the precipitate isremoved by filtration and dried in a vacuum oven at 70°-80° C. There isobtained 5.47 g. of the cyclized product. The elemental analysis of77.55% C and 3.10% N are in good agreement with the calculated valuesfor C₇₈ H₃₈ N₄ O₁₁ having the formula: ##STR45## When heated at 260° C.on a Fisher-Johns melting point apparatus, the polyimide becomesinsoluble and infusible.

EXAMPLE IV Preparation of Anhydride-Terminated Polyimide #1

Using the m-cresol benzene azeotropic procedure, there is allowed toreact benzophenone-tetracarboxylic acid anhydride (BTCA) (4.0279 g.,0.0125 mole) and 1,3-di(3-aminophenoxy)-benzene (DAPB-3,3) (2.9223 g.,0.01 mole) in 40 ml. of m-cresol and 10 ml. of benzene. There isobtained 5.7 g. of polyimide #2 which is a light yellow powder, solublein m-cresol, DMAC, sulfolane and dioxane. In a Fisher-Johns meltingpoint apparatus, this melts at 200° C. The TGA in air shows losses of 1%at 200° C., 3% at 300° C., 4% at 400° C., 5% at 500° C. and 17% at 600°C. The elemental analysis is C: 71.4% and H: 3.2%, which are inexcellent agreement with the calculated values of C₁₅₇ H₈₀ N₈ O₃₅ forthe formula:

    O(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 [NC.sub.6 H.sub.4 OC.sub.6 H.sub.4 OC.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 ].sub.4 O

EXAMPLE V Preparation of Imide of Anhydride-Terminated Polymer #2

In the same equipment used in Example III, there is added 5.2 g. ofpolyimide, #2, 40 ml. of m-cresol, and 1.1 g. of H₂ NC₆ H₄C.tbd.C--CH--C₆ H₅ and the mixture is heated at reflux until no morewater is collected in the Dean-Stark trap. The elemental analysis isfound to show C: 75.43% and H: 3.19%, which values are in good agreementwith the calculated values for C₁₈₉ H₉₆ N₁₀ O₃₃ having the formula:

    C.sub.6 H.sub.5 C.tbd.C--CH═CHC.sub.6 H.sub.4 --N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2

[NC₆ H₄ OC₆ H₄ N(OC)₂ --C₆ H₃ OCO₆ H₃ (CO)₂

]₄ N--C₆ H₄ C.tbd.C--CH═CH--C₆ H₅ POLYIMIDE # 2

EXAMPLE VI

There is added 4.0279 g. of BTCA to a mixture of 40 ml. of m-cresol and10 ml. of benzene in the flask of a continuous azeotroping apparatus.The Dean-Stark trap is filled with benzene, then there is added 0.808 g.of H₂ N--C₆ H₄ CH═CH.tbd.C--C₆ H₅ to the reaction mixture. The reactionmixture is heated at reflux for 15 minutes. Then there is added 2.9223g. of DAPB-3,3' and the mixture refluxed for four hours or until no morewater of reaction is formed. The product is isolated by the procedure ofExample V and is found to be identical to Polyimide #2 of Example V.

EXAMPLE VII Part I--Preparation of H₂ NC₆ H₄ OC₆ H₄ SO₂ C₆ H₄ OC₆ H₄ O₂SC₆ H₄ OC₆ H₄ NH₂

This synthesis involves first the preparation of4,4'-bis(4-chlorobenzenesulfonyl)diphenyl ether. Into a one liter roundbottom flask, equipped with a stirrer, nitrogen inlet tube and refluxcondenser, the top of which is attached to a bubbler and causticabsorber, is placed 165 grams (one mole) of diphenyl ether, 422 grams(two moles) of benzene sulfonyl chloride; and 16 grams (0.1 mole) ofanhydrous ferric chloride. The mixture is heated slowly to 174° C. overa period of six hours during which time the deep green solution slowlythickens. At the end of this period, the material is poured into abeaker to cool. The crude product is crystallized from approximately twotimes its volume of acetone. This material is found to weigh 466 grams(90%). Recrystallization gives material having a melting point by DSC of164° C. The second step is the preparation of 4-bis(4'-aminophenoxy)(4",4"'-diphenylsulfonyl)ether (BAPP). Into a 500 ml. flask equippedwith a stirrer, Dean-Stark trap and nitrogen inlet tube, is placed 66.1grams (0.606 moles) of para-aminophenol, and 24 grams (0.6 mole) ofsodium hydroxide dissolved in 25 ml. of water. Approximately 100 ml. oftoluene and 100 ml. of dimethylsulfoxide are then added. This mixture isheated to reflux under nitrogen and the water removed by the Dean-Starktrap. When no more water is collected in the trap, toluene is distilledfrom the mixture and an additional 100 ml. of dimethylsulfoxide isadded. To this solution is added 156.6 grams (0.30 moles) 4,4'-bis(4-chlorobenzenesulfonyl)diphenyl ether. This mixture is stirredunder nitrogen while the temperature is brought to 160° C., which ismaintained for one hour and 25 minutes, and then the product is cooledto room temperature. The resulting solution is then diluted with 2.5liters of water and made basic (pH of ≃8) with sodium hydroxide.Precipitation of the crude product is accomplished upon addition of thesodium hydroxide. The precipitate is collected, washed with water, andredissolved in three liters of dilute hydrochloric acid. This solutionis then slowly neutralized with sodium hydroxide to reprecipitate theproduct. After collecting the product on a Buchner funnel, it is washedagain with cold water and dried in a vacuum to yield 131 grams (65%) ofa creamed colored product having a DSC melting point of 265° C.

Part II--Preparation of Polyimide #3

The experimental procedure of Example VI is repeated except instead ofDAPB-3,3', there is used 6.64 g. of BAPP. After reaction there isisolated an almost quantitative yield of:

    C.sub.6 H.sub.5 C.tbd.C--CH═CHC.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2

[--NC₆ H₄ OC₆ H₄ SO₂ C₆ OC₆ H₄ --SO₂ C₆ H₄ OC₆ H₄ N(OC)₂ C₆ H₃ COC₆ H₃(CO)₂ ]

₄ ═NC₆ H₄ CH═CH--C.tbd.CC₆ H₅ POLYIMIDE # 3

The product is soluble in cresol, DMAC, DMF, DMSO, sulfolane anddioxane. The product becomes insoluble and infusible when heated at 250°C. The elemental analysis shows C: 69.34%, H: 3.14%, N: 3.07% whichvalues are in excellent agreement for the calculated values for C₂₆₁H₁₄₆ N₁₀ O₅₃ S₈.

EXAMPLE VIII Preparation of Anhydride-Terminated Oligomeric Polyimide #3

Using the m-cresol benzene azeotropic procedure, there is allowed toreact BTCA (3.6251 g., 0.01125 mole) and DAPB-3,3 (2.9223 g., 0.01 mole)in 40 ml. of m-cresol and 10 ml. of benzene. There is obtained 5.6071 g.of polyimide #3 which is a light yellow powder soluble in m-cresol,DMAC, sulfolane and dioxane. On a Fisher-Johns melting point apparatusthis melts at 120° C. with some evolution of gas. The TGA in air showslosses in air of 1% at 200° C.; 2% at 300° C.; 3% at 400° C.; 4% at 500°C. and 19% at 600° C. The elemental analysis shows 71.01% C, 3.22% H and4.60% N, which values are in excellent agreement with the calculatedvalues for the formula:

    O(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 [NC.sub.6 H.sub.4 OC.sub.6 H.sub.4 OC.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 ].sub.8 O

EXAMPLE IX Preparation of Anhydride-Terminated Oligomeric Polyimide #4

Using the procedure of Example III, there is reacted BTCA (12.0827 g.,0.0375 mole) and 3,3'-sulfonyldianiline (SDA) (7.4493 g., 0.03 mole) in80 ml. of m-cresol and 10 ml. of benzene. Polyimide #4 is obtained (16.9g.) which is a light yellow solid, soluble in m-cresol, DMAC, SMF andsulfolane. The lowest temperature at which a sample melts completelywhen dropped onto a preheated block is 255° C. The TGA in air showslosses of 2% at 200° C.; 3% at 300° C.; 4% at 400° C.; 7% at 500° C.;and 26% at 600° C. The elemental analysis is 63.9% C and 2.74% H, whichvalues are in excellent agreement with the calculated values for theformula:

    O(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 [NC.sub.6 H.sub.4 --SO.sub.2 --C.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 ].sub.3 O

EXAMPLE X Preparation of Anhydride-Terminated Polyimide #5

Using the procedure of Example III, BTCA (14.50 g., 0.045 mole) isreacted with SDA (9.9324 g., 0.04 mole) in 90 ml. of cresol and 20 ml.of benzene. Polyimide #5 is obtained (21.4 g.) which is a light yellowsolid, soluble in m-cresol, DMAC, DMF and sulfolane. The lowesttemperature at which a sample melts completely when dropped on apreheated block is 270° C. Its TGA in air shows losses of 0% at 200° C.;2% at 300° C.; 4% at 500° C. and 25% at 600° C. The elemental analysisshows 63.99% C, 2.73% H and 4.95% N, which values are in good agreementwith the calculated values for the formula:

    O(OC).sub.2 Chd 6H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 [NC.sub.6 H.sub.4 SO.sub.2 C.sub.6 H.sub.4 N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 ].sub.8 O

EXAMPLE XI Preparation of Anhydride-Terminated Oligomeric Polyimide #6

Using the same azeotropic techniques as shown, BTCA and2,4-diaminotoluene (DAT) are reacted in a molar ratio of 6 to 5 toobtain polyimide #6 whose elemental analysis conforms with the formula:

    O(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 [NC.sub.6 H.sub.3 (CH.sub.3)N(OC).sub.2 C.sub.6 H.sub.3 COC.sub.6 H.sub.3 (CO).sub.2 ].sub.5 O

EXAMPLE XII Preparation of Anhydride-Terminated Oligomeric Polyimide #7

Replacement of the BTCA in Example X by an equivalent amount ofpyromellitic dianhydride produces polyimide #7 which has the formula:

    O(OC).sub.2 C.sub.6 H.sub.2 (CO).sub.2 [NC.sub.6 H.sub.3 (CH.sub.3)N(OC).sub.2 C.sub.6 H.sub.2 (CO).sub.2 ].sub.5 O

EXAMPLE XIII

The anhydride-terminated polyimides #3, 4, 5, 6, and 7 are convertedindividually by the procedure of Example V to diacetylene-terminatedpolyimides by reaction with the three amines:

a. NH₂ C₆ H₄ CH═CH--C.tbd.CH

b. NH₂ C₆ H₄ CH═CH--C.tbd.CCH₃

c. NH₂ C₆ H₄ CH═CH--C.tbd.CC₆ H₅

These are summarized in Table I:

    ______________________________________                                        Polyimide #                                                                            Polyimide Anhydride Used                                                                       Aminoacetylene used                                 ______________________________________                                        4        #3               a                                                   5        #3               b                                                   6        #3               c                                                   7        #4               a                                                   8        #4               b                                                   9        #4               c                                                   10       #5               a                                                   11       #5               b                                                   12       #5               c                                                   13       #6               a                                                   14       #6               b                                                   15       #6               c                                                   16       #7               a                                                   17       #7               b                                                   18       #7               c                                                   ______________________________________                                    

When heated alone, or with small amounts of dicumyl peroxide, each ofthese yield insoluble, infusible crosslinked polymers.

EXAMPLE XIV

A mixture of 30 parts of polyimide #3, 70 parts of long fibered asbestosand 0.25 parts of cumyl peroxide is blended thoroughly and preformedinto a one-inch disc which is compression molded at 1000 pounds persquare inch at 265° C. for 5 minutes to yield a hard insoluble,infusible, molded product.

Similarly, a glass fiber reinforced composite is prepared byimpregnating 181 E Glass Fabric with a solution of polyimide #3 inN-methyl pyrrolidinone to a total resin content of about 35% and thesolvent removed by drying. The laminate is formed by stacking foursheets of impregnated glass fabric and curing at 250° C. at 200 poundsper square inch. The laminate is then post cured at 280° C. for 12 hoursand 300° C. for 12 hours and shows a flexural strength value of 52,600psi.

EXAMPLE XV

Using published procedures as given above, the following polyimidescontaining terminal groups that can function as dienophiles (DIENO) forthe vinylacetylenic donors of this invention are prepared and designatedas DIENO polyimides #1 to 6, inclusive. ##STR46##

These dieno polyimides are blended thoroughly by grinding in a mortarwith selected polyimides containing the terminal enyne groups of thisinvention. The mixtures spanned a wide range from 95 to 5; 50 to 50 and5 to 95 moles percent of the two components as shown in the followingtabulations:

    ______________________________________                                        Mixture of Polyimides with Dieno-Imides                                       Addition Polyimide     Diene                                                  Product  Used #        Used #  Mole Ratio                                     ______________________________________                                        A        1             1       95:5                                           B        1             1       50:50                                          C        1             1        5:95                                          D        2             2       95:5                                           E        2             2        5:95                                          F        2             3       50:50                                          G        3             3       50:50                                          H        4             4       50:50                                          I        6             4       50:50                                          J        8             1       50:50                                          K        12            5       50:50                                          L        12            4       50:50                                          M        15            6       95:5                                           N        15            6        5:95                                          O        15            6       95:5                                           P        18            5        5:95                                          Q        18            5       95:5                                           ______________________________________                                    

When these mixtures are heated at 275°-300° C. in a steel mold for 15minutes, insoluble, infusible addition products are obtained in allcases.

EXAMPLE XVI

When a mixture of 95 parts by weight of polyimide #2 ##STR47## and fiveparts of C₆ H₅ C.tbd.C--C.tbd.CC₆ H₅ are heated on a Fisher-Johnsmelting point apparatus, the softening point is lowered from about 252°C. to about 240° C., the viscosity of the melt is greatly reduced andthe yield of soluble, infusible product is quantitative.

The 1,4-diphenyl-buten-1-yne-3 is illustrative of diacetylenes of theformula ArCH═CH.tbd.CAr wherein Ar is the monovalent aryl groupcorresponding to the divalent Ar group of Formula I. Thus Ar representsan aromatic moiety containing at least 6 carbon atoms and preferably nomore than 21 carbon atoms.

The melting or softening points, as well as the viscosity of polyimides#1, 3, 6, 9, 12, 13, 15 and 18 are similarly reduced by the addition of5, 10 and 25 mole percent of C₆ H₅ CH═CH--C.tbd.CC₆ H₅ and C₆ H₅ OC₆ H₄CH═CH--C.tbd.CC₆ H₄ OC₆ H₅, respectively. Also, the same degree oflowering of viscosity and melting points are observed by the addition ofArCH═CH--C.tbd.CAr, specifically, C₆ H₅ CH═CH--C.tbd.CC₆ H₅ to the"Dieno" polyimides #1 to 6, inclusive. In all cases, insoluble,infusible addition products are obtained when the mixtures are heated tocuring temperatures.

EXAMPLE XVII

To a 4.52 g. of polyimide #3 in 30 ml. of dioxane is added 0.3 g. ofdimethyl diacetylene dicarboxylate and the mixture refluxed for twohours after which the dioxane is removed under vacuum at a pressure of 5mm leaving the adduct in which the two terminal --CH═CH--C.tbd.C--C₆ H₅groups have been converted to a phthalate derivative, ##STR48##Appropriate tests confirm that there are two methyl carboxylate groupsin the molecule. Replacement of the acetylene dicarboxylate by otherdienophiles such as ethyl acrylate, diethyl acetylene dicarboxylate,styrene and N-phenyl maleimide also results in a Diels-Alder additionproduct.

EXAMPLE XVIII

The procedure of Example IV is repeated with appropriate modificationsin the molar amount of benzophenone-tetracarboxylic acid anhydride(BTCA) to give an anhydride-terminated polyimide having a formulacorresponding to anhydride-terminated polyimide #2 except that the nvalue is 18 instead of 4. Then this dianhydride is used in the procedureof Example V using the appropriate molar amount of H₂ NC₆ H₄CH═CH--C.tbd.CC₆ H₅ to give an imide derivative similar to that obtainedin Example V except that the value of n in this imide derivative is 18instead of 4. The procedure of Example V is repeated three times usingthe following as the vinylacetylene amines instead of that used inExample V:

a. NH₂ C₆ H₄ CH═CH--C.tbd.CH

b. NH₂ C₆ H₄ CH═CH--C.tbd.CCH₃

c. NH₂ C₆ H₄ CH═CH--C.tbd.CC₆ H₅

The corresponding vinylacetylene-terminated polyimides of Formula I areobtained in which n has a value of 18. Reactions of equivalent amountsof these respective vinylacetylene-terminated polyimides withdienophiles in accordance with the materials and procedures of ExamplesXVI, XVII and XIX give results similar to those obtained in theserespective examples.

EXAMPLE XIX

The procedure of Example V is repeated a number of times to preparepolyimides having terminal groups of the formula RCH═C(R)--R'--N byreaction individually of polyimides #3, 4, 5, 6 and 7 each with thefollowing amines respectively:

a. NH₂ CH₂ C═CH₂

b. NH₂ C₆ H₄ CH═CH₂

c. NH₂ CH₂ CH₂ CH═CH₂

d. NH₂ CH₂ CH═CHCH₃

In the above formula, R is as defined above, preferably hydrogen,methyl, phenyl or ethyl, and R' is a divalent radical to 1-20,preferably 1-10 carbon atoms including alkylene and arylene radicalsincluding those defined above for Ar, preferably methylene, ethylene,propylene, phenylene, etc.

Each of these products is mixed with 5% and 25% by weight respectivelyof the following vinylacetylenes:

    C.sub.6 H.sub.5 --CH═CHC.tbd.CC.sub.6 H.sub.5

    C.sub.6 H.sub.5 CH.sub.2 CH═CHC.tbd.CCH.sub.2 C.sub.6 H.sub.5

    CH.sub.3 CH═CHC.tbd.CCH.sub.3

    C.sub.2 H.sub.5 CH═CHC.tbd.CC.sub.2 H.sub.5

In each case the resultant product when heated by itself or with a smallamount of dicumyl peroxide gives an insoluble, infusible crosslinkedpolymer which is suitable for molding.

In some dienophiles there may be a single acetylenic or non-conjugatedtwo or more acetylenic groups. To distinguish from the conjugated groupsof this invention, these groups may be referred to as non-conjugatedacetylenic groups.

While it is contemplated that the conjugated diacetylene-terminatedpolyimides of this invention are covered by the above Formula I, it isalso contemplated that the polyimide between the two terminal groups maybe interrupted by a joining group of a different type. For example, inpreparing the polyimide inner structure, it is possible to use a diamineof the structure H₂ N--Ar--Z--ArNH₂ in place of one or more molecules ofthe H₂ N--Ar--NH₂ used in preparing the starting polyimide to which theterminal conjugated diacetylene groups are attached. In such case thereare one or more Z groups in the inner part of the polymer molecules aswell as in the terminal groups.

It is also contemplated that side branches may be formed by using a tri-or tetra-amino aromatic compound in place of small amounts of thediamine used in preparing the polyimide inner structure. Upon formationof the polyimide by reaction with the dianhydride, one or more sidechains or branches will be formed so that ultimately there may be threeor more terminals to which may be attached the conjugated diacetylenegroups.

It is intended that these contemplated variations are included withinthe scope of the invention described herein.

For example, when the polyimide structure is prepared using H₂ NArZArNH₂as a portion of the diamine, there may be obtained a random copolymer inwhich the Z groups are distributed at random throughout the polyimidelinear chain or may be in blocks, depending on how the Z-containingdiamine is added. Thus if this diamine is admixed with one or more otherdiamines before the diamines are reacted with the dianhydride to formthe polyimide, then a random copolymer will be produced. However, if thediamines are reacted separately, then block copolymers will be produced,possibly with homopolyimides of either or both types of diamines beingpresent as byproducts. The dipolymers may be represented by thefollowing formula: ##STR49## wherein R, Z, Ar, Ar', n and n' have thesame definitions as given above.

As indicated above, the units within the n' brackets may be present as asingle block or a plurality of blocks in a particular polymer moleculeor may be dispersed at random between units of the type within the nbrackets.

In the polyimide derivatives of this invention the Ar, Ar' and R groupsar preferably hydrocarbon or hydrocarbon groups joined by various othergroups as described above. However, there may also be varioussubstituent groups present so long as they do not interfere with thereactions or functions described herein. The Ar and Ar' groupspreferably comprise benzenoid radicals as illustrated.

Dienophiles that are reactive with the polyimides of this inventioninclude those of the following formulas having the portion Q' whichrepresents a polyimide portion of the formula: ##STR50## wherein thesymbols have the same definitions as given above: ##STR51##

    CH.sub.2 ═CHR'N(OC).sub.2 Ar'(CO).sub.2 ═Q═N--R'CH═CH.sub.2

    R°C.tbd.C--R'--N(OC).sub.2 Ar'(CO).sub.2 ═Q═N--R'C.tbd.CR°

    R°C.tbd.CAr"═(CO).sub.2 ═Q═NArN(OC).sub.2 ═Ar"C.tbd.CR

    R°C═CHAr"═(CO.sub.2)═Q═NArN(OC).sub.2 ═Ar"CH═CR°

and Ar" is a trivalent aromatic radical having the same basic ringstructure as Ar.

While certain features of this invention have been described in detailwith respect to various embodiments thereof, it will of course beapparent that other modifications can be made within the spirit andscope of this invention, and it is not intended to limit the inventionto the exact details insofar as they are defined in the followingclaims.

The invention claimed is:
 1. A polyimide of the formula: ##STR52##wherein: Ar' is a tetravalent aromatic radical, the four carbonyl groupsbeing attached directly to separate carbon atoms of said aromaticradical and each pair of carbonyl groups being attached to adjacentcarbon atoms in Ar' except that in the case of Ar' being a naphthaleneradical, one or both pairs of the carbonyl groups may be attached toperi-carbon atoms;Ar is a divalent aromatic radical; n is an integerhaving a value of one to 20; R is hydrogen or an organic moietycontaining one to 21 carbon atoms; and Z is the structure--CH═CH--C.tbd.C-- or --C.tbd.C--CH═CH--.
 2. The polyimide of claim 1,in which R is H.
 3. The polyimide of claim 1, in which R is C₆ H₅. 4.The polyimide of claim 1, in which R is CH₃.
 5. The polyimide of claim1, in which n is at least two.
 6. The polyimide of claim 1, in which nis at least three.
 7. The polyimide of claim 5, in which Ar' is aradical selected from the class consisting of: ##STR53##
 8. Thepolyimide of claim 1, in which Ar' is ##STR54##
 9. The polyimide ofclaim 1, in which the Ar attached to Z is selected from the classconsisting of --C₆ H₄ --, --C₆ H₄ OC₆ H₄ -- and --C₆ H₄ SO₂ C₆ H₄ --.10. The polyimide of claim 5, in which the Ar attached to Z is --C₆ H₄--.
 11. The product of claim 1, in which the polyimide is prepared bythe reaction of a dianhydride of an aromatic tetracarboxylic acid and adiamine selected from the class consisting of:1,3- and 1,4-(NH₂)₂benzene; 2,3-; 2,4-; 2,6- and 3,5-(NH₂)₂ -toluene 3,3'-; 4,4'- and3,4'-methylene dianiline 4,4'-; 3,3'- and 3,4'-oxydianiline; 4,4'-;3,3'- and 3,4'-sulfonyldianiline; 1,3-; 1,4- and 1,2-bis(3-aminophenoxy)benzene; 1,3- and 1,4-bis(4-aminophenoxy) benzene; and H₂ NC₆ H₄ OC₆ H₄SO₂ C₆ H₄ OC₆ H₄ SO₂ C₆ H₄ OC₆ H₄ NH₂ in which the respectiveattachments to a C₆ H₄ ring are meta or para to each other.
 12. Thepolyimide of claim 11, in which the diamine is a methylene dianiline.13. The polyimide of claim 11, in which the diamine is a sulfonyldianiline.
 14. The polyimide of claim 11, in which the diamine is anoxydianiline.
 15. The polyimide of claim 11, in which the diamine is2,4-toluene diamine.
 16. The polyimide of claim 11, in which R is H. 17.The polyimide of claim 11, in which R is C₆ H₅.
 18. The process ofpreparing a polyimide of claim 1, which comprises first reacting anamine of the formula H₂ NArCH═CH--C.tbd.CR with an anhydride of theformula: ##STR55## wherein n, Ar, R and Ar' are the same as defined inclaim 1, to form a hemiamic acid intermediate and then the saidintermediate is dehydrated to form the cyclic imide structure ofclaim
 1. 19. The hemi-amic acid intermediate obtained in the first stepof claim 18, having the formula: ##STR56##
 20. The hemi-amic acidintermediate of claim 19 derived by reaction of n+1 moles of ##STR57## nmoles of NH₂ ArNH₂ and two moles of H₂ NArC.tbd.C--C.tbd.CR--, saidintermediate having the formula: ##STR58## wherein R, Ar, Ar' and n havethe same meaning as in claim
 1. 21. The hemi-amic acid of claim 19, inwhich Ar' is ##STR59## and RCH═CH--C.tbd.CAr-- is C₆ H₅--CH═CH--C.tbd.C--C₆ H₄.
 22. The hemi-amic acid of claim 20, in whichAr' is ##STR60## and RCH═CH--C.tbd.C--Ar is C₆ H₅ CH═CH--C.tbd.C--C₆ H₄.23. The polyimide of claim 1 in which n has a value of one to
 10. 24.The polyimide of claim 5 in which n has a value of one to
 10. 25. Thepolyimide of claim 7 in which n has a value of one to
 10. 26. Thepolyimide of claim 11 in which n has a value of one to
 10. 27. Amonomeric diimide of the formula: ##STR61## in which: R is hydrogen oran organic moiety containing 1 to 21 carbon atoms;Ar is a divalentaromatic organic radical; Ar' is a tetravalent aromatic organic radical,the four carbonyl groups being attached directly to separate carbonatoms of said aromatic radical and each pair of carbonyl groups beingattached to adjacent carbon atoms in Ar' except that in the case of Ar'being a naphthalene radical, one or both pairs of carbonyl groups may beattached to peri-carbon atoms therein; and Z is the structure--CH═CH--C.tbd.C-- or --C.tbd.C--CH═CH--.